The G-Technology 4TB G-Drive Pro 7200 RPM Storage System with Dual Thunderbolt Ports is an external hard drive that contains four 2.5" drives in a RAID 0 array, and is designed to provide you with ample storage and fast transfer rates of up to 480 MB/s combined. The unit features a 7200 RPM SATA III hard disk and two thunderbolt ports for high speed connectivity and daisy-chain functionality, with the ability to chain up to five additional devices.